Track wheel for vehicles



TRACK WHEEL FOR VEHICLES Filed Feb. 25, 1947 l l 'll F/Gl.

Inventor 0110' S i nger m m w A l tor/1e y l April 27, Q $|NGER 2,440,417

' TRACK WHEEL FOR VEHICLES- Filed Feb. 25, 1947 v 2 Sheets-Sheet 2 F/GZ.

[nuentr Orm Singer 1 MAM/2m 6A;

A ltorney Patented Apr. 27, 1948 TRACK WHEEL FORVEHICIJES QttorSingcnLondun; England Apnlication February. 25, 194'Z1QSerialN0. T301698 lnGreatflritain March 16; 1946" This invention relatesto track Wheel for vehicl'es; that is to say-wheels whichlay' a track on the ground increasing the areas of support:- or contact. as compared with that of: a normal Wheel;

It is an object of this invention-to-provide a track wheel which will be equivalent to a wheel of" large diameter rolling: on the ground; and capable "of transmitting a powerful tractive effort in the ease'of a driven wheel.

Another object is to provide asimple mechanical construction avoiding the necessity fongearine, or chains whileconnecting the moving parts together by linkages which" ensure the maintenance of the required angular relationships: between them;

Yet another object is to provide a construction in which there are no sliding parts which are liable to be obstructed by caked deposits', mud and'the like.

In many constructions hitherto-used a track which is laid consistsof linkedelementson which wheelssupporting the vehicleroll fo'rwardL Such track layers are noisy in use andrhave-other disadvantages;

According to the inventiona track'iwheel has track: sections hinged: together: and connected at intervals by links to: pivoted crank-s while means are". provided for: maintaining arms; or, equivalent members, fixedly associated withthe cranks in. mutually parallel. relationship;

A simpleform': of. track wheel. according 20': the present invention comprises a; hub: whiclixturns onits central: axis and carries a; number of cranks, rotating on: crank shafts. spaced: apart around the centra1 axis; each crank being?- linked to'a joint'in the track' sections whichltraclczseee tions are joinedtogether so asto. form a: con? tinuous track. Each: track? sectiontis; generally curved toa large radius on its tread suriaceralthough theform. 01% the. curve may. be.- varied"; The track sectionsmay'be rigid or to somezextent flexible; and; they maybe provided: with: tread surfaces which area roughened: for agricultural purposes; or may have: treads of rubhen or the likeifor running on'roads: The'crankshaftsscarry also additional cranks or'arms orequivalent meme bers: provided with'pivots-bywhich they are-inten connectedby asubstantially rigidv body; such a ring or star shapedamember so astmmaihtain them: in mutually: parallel relationship;- as: they rotate; The angular relation between each crank and: arm varies; progressively round the-- hulzn so that the traclermay'assume a flattened iormzwith its, longeraxis approximately parallel: to, the

2': ground; and thus proceed as the hub rotates; so that its centre remainsat a. substantiazlhr. uniform? height above the ground. The; differenoe-in angle between adjacent cranks and arms isgenerally equal to threehundred. and:

sixty degrees divided by: the number: of: cranks: For" example 1 the progressive change; in angle is six-tw degrees" in: the case of six cranks, and fortyfivedegrees in the case of eight cranks; The track Wheel may: have any: othernumbers of trach sections; either an even a or an 7 odd number, subject of course t'o the degree of: mechanised complexity involved;

Thein'vention' is:llliistratedv by waybi example in the accompanying drawings in". which z Figurel isan elevation of a linkedtrackzwheel with part -of the hub cover: broken i away 'tolshow the armswonnected to-the ring; and:

Figure is an end elevation in section drawn to a. larger: scale and: taken: on the linen-II: in Fig. 11

In thi s example, a=simple-constructionzof trackwheel is described in". which there are six: equal track sections 1', eachzprevidedwithla- .trteadisurrface'lr preferably curvedtto a; radiusacorresponding with' that of the largeswheel to." which; the construction isequivalent'; Each; trackrseotion is further providedwith a pair; of: lugs 3: at one end 'andia: single: lug": t4 atithemth'er sorthatl they; interlock; oneuwitli the other and are-.- joined in at. continuous: chain by' pivots on hinges;v I it" each of which: passes through". the pairv of: lugs" 13. of

, one track section: and through: the; single; lug; it

ofzthenexti. Thettrachisiconnectedto an axle-ref a vehicle (not: shown) I by a symmetrical arrangement in) which aisystema of outercranks l? and links Ht connecting: the pivotstoa hub i9? at.- tached'tozthe axle-:is duplicated on;the-tw0 sides of; the hub with: the: object of eliminating; avoidablestresses:imtheconnectingmembeis;. A: pair of; links I8 is accordingiyt freely pivoted to each pivot; 16 joining; the track sections 5 i each link havingsa bearing recessi 2! fitting over one. end of; a; PEYQtifilHdilGbfiiHGdthSfDIl by the head, of a bolt 22 which. threadedlywngaged: inrthe. pivot and prevented fromturning:v by; a locking. tag 23; The otherl'end: ofaeachlink carries a' ballbearing fliwhichdsiretained in-aareeess: 26: in; theelink by aidust. oap-21 boltedtort-heslink; and which bears on; a. pin 28,: securedlinran. outen-crank Ll. Two such omen-cranks. I T associatedzwith: each pair; of lings It are: arranged; so: as: to: rotate in; parallel relationshipv about one: of; six axes fixed relative to theehub, equidistant fromeachnther andfrom thew-centre of thezhub The hub comprises a crank case 29 and cover 3| together enclosing a toroidal space 32 of rectangular cross section and a flange 33 which is welded to the inner external surface of the crank case and provided with fixing holes 34 for connection with an axle. The crank case 29 and cover 3| are provided with bearing housings 35 arranged concentric with each of the six axes of rotation of the outer, cranks ll. Each crank shaft 37, mounted at one of the positions by tapered roller bearings 38 in the bearing housings 38 of the crank case and cover, comprises a pair of coaxial stub shafts having projecting ends 39 either side of the hub provided with square shanks on which are held the ends of corresponding outer cranks ll. The ends referred to are of course those remote from the ends connected to the links l8, and they are retained on the stub shafts by nuts 42 on threaded ends 39 of the stub shafts extending from the square shanks. Locking tags 63 are provided to hold the nuts tightly engaged.

It may be mentioned that a seal for excluding dirt from the tapered roller bearings comprises a pair of conical Washers it and l! of hardened steel sandwiched between conical rubber washers 48 and 59 the outer one 48 of which restsagainst an internal conical surface in the bearing housing 33 while the inner one rests against an external conical surface on a collar s4 surrounding the stub shaft. Since the coefficient of friction between steel and steel is less than that between rubber and steel, relative rotation will take place between the steel washers which will provide an effective seal on account of their flexibility and resilient support. If desired the rubber washers may be vulcanized to their respective supports.

The adjacent ends of the coaxial stub shafts are fixed to inner cranks which have a crank pin 52 extending fixedly between them providing a support for a ball bearing 53 mounted in a ringor spider 54 which encircles the torodial space in the hub. The ring has six such bearings mounted evenly about a common centre.

Having now described the principal components of the track wheel, it will be convenient to give some account of their relative disposition and mode of operation. Like elements mentioned, being respectively the track sections ll, links l8, outer cranks H and inner cranks SI are of the same length, the only distinguishing feature being that at the six positions around the hub, the inner and outer cranks are fixed together in relatively different angular relationship. The bearings 38 in the hub and the bearings 53 in the ring 55 are spaced equally on equal pitch circles so that the inner cranks between them all must lie parallel in any position, whereas the outer cranks H are arranged so that when one crankshaft lies vertically below the centre of the hub, the pair of outer cranks 11 secured to it extends vertically upward and the pair of outer cranks ll on the diametrically opposed crankshaft 31 extends vertically downward. The remaining outer cranks ll on each side of the centre converge, each outer crank being inclined to the vertical at an angle of sixty degrees. In other words, starting from the bottom crankshaft 3T and going around the hub in an anticlockwise direction, each pair of cranks H is advanced through an angle of sixty degrees in a clockwise direction with respect to the previous one. This angular relationship must hold good irrespective of the angular position of the hub.

It will be seen from Fig. 1 that a downward load on the axle directed toward the track supporting surface must cause the track wheel to assume a configuration of stable equilibrium in which the track sections follow approximately an ellipse whose major axis lies substantially parallel to the supporting surface. The hub I9 carrying the cranks rotates but its centre remains at a substantially uniform height above the ground as it travels over the track sections H which bear on the ground at any time. The cranks are however controlled by their linkages so that they rotate in a direction opposite to that of the hub at the same mean speed.

The curvature of the treads has been mentioned as having a radius corresponding approximately with that of the large wheel to which the device is equivalent. Actually the curvature is not truly circular but is a rolling curve approximating to a circular curve with the object of providing a more uniform motion. Thelinks l8, instead of being connected to the hinge-pivots it, may be connected to the respective track sections 1 l near to such hinge pivots.

The track wheel may be a supporting wheel only, or it may be positively driven through its hub IQ, for example.

I claim:

1. A track wheel comprising a hub member, a plurality of track sections jointed together and constituting an endless track, a plurality of crank shafts disposed in spaced relation around the axis of said hub member, outer cranks on said crank shafts displaced in their relative angular positions successively around said hub member, links extending from points adjacent the joints between said track sections to said outer cranks, and means for causing said crank shafts to rotate synchronously in one direction of rotation as said hub member rotates in the opposite direction, comprising inner cranks on said crank shafts so disposed as normally to extend parallel to one another, and means inter-connecting said inner cranks adapted to cause them to maintain said parallel relation.

2. A track wheel according to claim 1 wherein the means interconnecting said inner cranks comprises a substantially rigid spider to which each of said inner cranks is connected.

3. A track wheel comprising a hub member, a plurality of track sections jointed together and constituting an endless track, a plurality of crank shafts disposed in spaced relation around the axis of said hub member, outer cranks on the ends of said crank shafts at each side of said hub member, the outer cranks on each such crank shaft being angularly displaced relatively to the outer cranks on other crank shafts, at either side thereof around said hub member, links extending from both ends of the joints between said track sections to said outer cranks, inner cranks on said crank shafts normally extending parallel to one another and means interconnecting said in-' ner cranks adapted to maintain their parallel re-' lationship as said hub rotates.

4. A track wheel comprising a hub member, a plurality of track sections with means jointing them together end to end constituting an endless track, a plurality of crank shafts disposed in spaced relation around the axis of said hub member, each such crank shaft having a pair of cranks one crank at each end thereof, the cranks of one crankshaft being angularly displaced relatively to those of adjacent crank shafts around said hub member, a pair of links extending from adjacent each joint in said track sections to the cranks of a corresponding crank shaft at each side of said hub member, an inner crank on each said crank shaft, said inner cranks being normally all parallel to one another, and an annular member extending around said hub and interconnecting all of said inner cranks whereby to maintain their parallel relationship as said hub rotates.

5. A track wheel according to claim 1 having said outer cranks and. links duplicated at each side 6 of said hub member, the hub member itself comprising a crank case enclosing both said inner cranks and the means interconnecting the same, hearings in said crank case through which said crank shafts extend toward either side thereof, said outer cranks being affixed to the projecting ends of said crankshafts outside said crank case.

O'I'IO SINGER. 

